Acutely injured tissues generally undergo a well-choreographed set of repair processes, usually characterized in three major phases: the inflammatory phase, initiated almost immediately after trauma occurs (lasting from 1-3 days); the proliferative phase, in which new tissue is formed (lasting from 3 to 14 days); and the remodeling phase, involving wound contraction, accumulation of collagen, and scar formation (this final phase can last for several months).
In contrast, chronic wounds fail to exhibit any well-defined healing processes. Some wounds remain in a state of chronic inflammation, while others simply fail to initiate tissue regrowth. Chronic wounds will often remain refractory to traditional treatments for years. For venous stasis ulcers, this is a particularly vexing problem; standard compression therapy only works on about 50% of the time, and there are few alternative treatments. Currently there are approximately 1.3 million individuals who suffer from these wounds in the U.S., with a treatment cost of over $730 million in 1998.
Factors leading to the failure of chronic wounds to heal are largely unknown. In fact, the entire process by which chronic wounds fail to heal is poorly understood. If factors and mechanisms contributing to the failure of healing in chronic wounds were identified, new treatment regimens could be developed. Therefore, a need exists for biomarkers of chronic wounds and for new procedures and formulations for treating wounds.